1. Field of the Invention
The present invention relates to an ink jet head cartridge in which a print head and an ink container for supplying ink to the print head are integrated, a print head, and an ink container. In particular, the present invention relates to stress between an ink container and a printing element substrate caused due to a temperature change. The present invention also relates to a method for manufacturing the ink jet head cartridge.
2. Description of the Related Art
An ink jet printing apparatus is a printing apparatus based on a so-called non-impact printing method and is characterized in that this apparatus causes very small noise during a printing operation. This apparatus also can be used to perform a high-speed printing to various printing media. By the above characteristics, the ink jet printing apparatus has been widely used as an apparatus for providing a printing mechanism for a printer, a copier, a facsimile, a word processor or the like.
Print head provided in the ink jet printing apparatus as described above include the one that uses an electrothermal conversion element having a heat generation resistance member to heat ink to use a film boiling to eject ink droplets. An ink jet print head using the electrothermal conversion element as described above is structured so that an electrothermal conversion element is provided in a printing liquid chamber. When a printing operation is performed, an electric pulse is supplied to the electrothermal conversion element based on a printing signal to generate heat to apply thermal energy to ink. Then, a bubble pressure of bubble formation (boiling) in ink due to a phase change of printing liquid is used to eject ink droplets through minute ejection openings. In this manner, ink droplets are ejected from a print head to print ink on a printing medium.
The ink jet print head ejects ink in a relatively small size and requires liquid droplets to be adhered to a paper with a high accuracy. Thus, when a printing element substrate is deformed, a significant influence is caused on the performance of the printing apparatus. Thus, such deformation is desirably minimized.
On the other hand, ink jet print heads in recent years tend to have been required to have a smaller size and a low profile. In order to satisfy such a demand, a print head integrated with an ink container for storing ink has been suggested.
This integrated ink jet head cartridge type ink jet print head has an ink container that is generally manufactured by molding resin because of its easy manufacture and cost for example. By using resin molding, a complicated shape can be manufactured. Furthermore, a part of this ink container has a joint area having a flat surface with a high degree of accuracy so that this part can be directly joined with a printing element substrate. This joint area also can use resin molding to secure a flat surface with a high degree of accuracy.
By adhering a printing element substrate to this joint area by adhesive agent for example, an ink jet print head can be assembled with a simple structure. Furthermore, an ink jet print head with a low cost and a high performance can be manufactured in the manner as described above.
Japanese Patent Laid-Open No. 2005-342994 describes an example of this integrated-type ink jet head cartridge and describes the structure of the ink jet head cartridge and the manufacture method thereof. According to Japanese Patent Laid-Open No. 2005-342994, a printing element substrate is adhered and fixed to an ink container by adhesive agent or the like. FIGS. 9A and 9B show an example of an ink jet head cartridge to which a printing element substrate is adhered.
By the way, the conventional ink jet head cartridge as shown in FIGS. 9A and 9B is structured so that container-side ink supply opening H5201, H5202, and H5203 are arranged in parallel with one another in a direction along which nozzles are arranged. A substrate-side ink supply opening H5102a, H5102b, and H5102c have communication with the container-side ink supply openings H5201, H5202, and H5203. The substrate-side ink supply openings H5102a, H5102b, and H5102c are also arranged in parallel with one another in a direction along which nozzles are arranged. However, in this case, a problem is caused in which the ink container H5501 manufactured by resin as described above and the joint area of the printing element substrate H5101 manufactured by silicon connect with each other and cause the deformation of the printing element substrate H5101. Specifically, when the ink container H5501 is manufactured by die forming, resin flows in a nozzle arrangement direction among the ink supply openings H5201, H5202, and H5203 in the side of ink container H5501. Thus, after the molding, glass filler included in resin tends to be in a direction in parallel with the nozzle arrangement direction. In this case, a linear expansion coefficient of resin in a direction orthogonal to a direction along which glass filler is oriented is higher than that of resin in a direction along which the glass filler is oriented. On the other hand, the printing element substrate H5101 formed by silicon is adhered to the ink container H5501. Then, silicon and resin basically have different linear expansion coefficients and a direction orthogonal to a direction along which glass filler is included in resin has a relatively high linear expansion coefficient as described above. This causes a large difference in the linear expansion coefficient between silicon and resin at the joint area of the ink container H5501 and the printing element substrate H5101. Thus, when environmental temperature of the ink jet head cartridge changes, the large difference in the linear expansion coefficient causes the deformation of the printing element substrate and the ink container. As a consequence, an influence is caused on the ink ejecting performance of the print head.
For example, the ink jet head cartridge having the structure and material characteristic as described above must be maintained at a high temperature in order to cure thermoset-type adhesive agent in an assembly step. This step heats the ink jet head cartridge to a temperature of 100 deg C. or more. Thus, adhesive agent cured at 100 deg C. causes a difference in the linear expansion coefficient between silicon and resin, and thus causes stress between the materials due to the shrinkage for Δ75 deg C. Furthermore, when a physical distribution status is considered to consider a low temperature environment of −30 deg C., the stress between the materials for Δ55 deg C. is caused additionally. The larger the difference in the linear expansion coefficient is, the higher the stress caused between materials is. Thus, a risk is caused where the product may deform due to the residual stress due to the difference in the linear expansion coefficient.
In particular, when an ink jet head cartridge can eject a plurality of colors of ink (e.g., when a printing element substrate has an integrated structure of three colors of C, M, and Y), the respective ink supply openings for supplying the respective colors of ink are arranged in parallel with the nozzle arrangement direction. The characters C, M, and Y represent the colors of cyan, magenta, and yellow. When nozzle arrays of the respective colors have a narrow distance thereamong, a member constituting the part has an elongated shape. Thus, strengths of an ink container and a printing element substrate for a direction orthogonal to the nozzle arrangement direction are lower in this structure, and cause the ink container and the printing element substrate to easily deform, respectively.